         window.onload = function(){
         getRem(750,100)
         };
         window.onresize = function(){
         getRem(750,100)
         };
         function getRem(pwidth,prem){
           var html = document.getElementsByTagName("html")[0];
           var oWidth = document.body.clientWidth || document.documentElement.clientWidth;
            html.style.fontSize = oWidth/pwidth*prem + "px";
         }
       